I'm studying Spanish abroad in Spain, and the other day I just saw a movie (or at least I was told it was one) on the television. There was a riveting sequence where one of the characters, played by a blond actress, snuck into a family's home at night while armed with a knife. She attacked the mother, who was sleeping, and the son didn't hear because he was listening to music in his headphones. The intruder stabbed the daughter when she tried to call the police. Her brother eventually locked himself and her in a room while the murderous lady stood in the hallway and tried to break in the door with a hammer.
These are the salient details I remember, but I don't have much other information. My rudimentary understanding of Spanish gave me the notion that the knife lady was an angry ex-lover or something similar trying to get revenge on the father of the family.
TIA for any help!